On Monday, a group of 21 youth plaintiffs currently suing the federal government over climate change will go before a federal court to argue that their case — which legal experts have classified as a groundbreaking piece of climate litigation — should be allowed to proceed to trial.

On the other side of the court will be lawyers for the Trump administration, who will argue that the mere process of preparing for trial — sifting through decades of government documents and communication with fossil fuel companies, among other things — would constitute an overwhelming burden.

Ultimately, the Ninth Circuit Court of Appeals will decide whether the case can move forward to trial — a decision that could shape the future of climate litigation for years to come.

“The Ninth Circuit faces a simple question with profound consequences: Should people have access to the courts when the federal government threatens their fundamental rights?” Carroll Muffett, president of the Center for International Environmental Law, told ThinkProgress via email. “The Trump Administration argues that the government could actually render the climate incapable of sustaining human life without violating the Constitution. It’s a claim as chilling as it is extraordinary; and it should be rejected.”

The hearing on Monday is hardly the first time the plaintiffs have had to make their case before a judge — but it is potentially the final barrier that must be crossed before the plaintiffs can argue their case in a trial, which would be the first trial to consider whether the government’s actions on climate change actually violate the U.S. Constitution.

“The Juliana case is about much more than children’s rights or even climate change,” James May, a professor at the Widener University School of Law, told ThinkProgress. “It is about the power of the executive to constrain the ability of an independent judiciary to perform its core function of interpreting the constitution.”

The plaintiffs — who range in age from ten to 21 — base their case on a theory known as the public trust doctrine, which holds that the United States government must maintain and protect certain commonly-held resources, like rivers, or seashores, for use by the public.

The plaintiffs in the youth climate case take the doctrine one step further, arguing that the atmosphere, as a commonly-held element, qualifies for protection by the government as part of the public trust. By failing to act to stave off the worst impacts of climate change — and by actually undermining climate action, through things like fossil fuel subsidies — the plaintiffs argue that the government has in essence violated their constitutional right to a protected atmosphere. The plaintiffs also argue that the government, through its actions, has denied them due process under the Fifth Amendment of the Constitution, which holds that the federal government cannot deprive a person of “life, liberty, or property” without “due process of law.”

“What this litigation does is it fast forwards that constitutional principle to the modern urgency of climate crisis,” Mary Woods, a law professor at the University of Oregon who first proposed applying public trust doctrine to the atmosphere, told ThinkProgress in 2015. “It’s a very simple extension of logic. If navigable waters were crucial to the public back then, certainly the air, atmosphere, and climate systems warrant protection as public trust systems as well.”

The case was initially scheduled to go to trial on February 5 in Oregon, after U.S. District Court Judge Ann Aiken ruled in November of 2016 that the plaintiffs had sufficiently proven that they were likely to suffer personal damages due to climate change. Initially filed against the Obama administration in August of 2015, the youth plaintiffs named President Donald Trump as a defendant in the case when Trump took office in January.

Since being named as a defendant, the Trump administration has fought all attempts to bring the case to trial, filing an appeal of Aiken’s November decision in March. In June, Aiken denied the administration’s appeal — only for the administration to file another appeal with the Ninth Circuit court in June. That appeal, known as a writ of manadmus, asked the higher court to reconsider Aiken’s decision to allow the case to move to trial, and asks the court to use its supervisory powers to “end this clearly improper attempt to have the judiciary decide important questions of energy and environmental policy to the exclusion of the elected branches of government.”

Following the administration’s appeal, the Ninth Circuit temporarily paused all proceedings in the case until a decision could be reached. The hearing on Monday will take place before a three judge panel comprised of Chief Judge Sidney Thomas, a Clinton-appointee, Circuit Judges Alex Kozinski, a Reagan-appointee, and Marsha Berzon, a Clinton-appointee. The defendants and plaintiffs will each get 20 minutes for arguments, with the administration going first.

“Rather than forthrightly address the issues and defend the case at trial, the government has filed an emergency motion that seeks to circumvent the ordinary processes of adjudication,” Doug Kysar, a professor at Yale Law School who joined a group of legal experts in filing a brief in support of the plaintiffs case, told ThinkProgress. “The real emergency here is what’s happening to the climate — not the government’s claimed emergency that it would be too burdensome to explain to the court why it has chosen to gamble with the planet’s very ability to support life.”

Eric Grant, who was appointed to be a Deputy Assistant Attorney General in the U.S. Department of Justice for the Trump administration in April, will likely argue that, among other things, the pre-trial process involved in the case would include a discovery process that would likely force the government to uncover decade’s worth of information on climate change, from federal science to communications with fossil fuel companies. The federal government has argued that the breadth of discovery required by the case would be overly onerous.

But Grant will likely also argue that the plaintiffs lack standing — or the ability to prove that they would suffer sufficient harm from a particular law or, in this case, action — to bring their complaint before a court. In November, Judge Aiken found that the plaintiffs had proved sufficient standing in arguing personal damage from climate change, citing things like ocean acidification or wildfires that threaten food sources and property. But the issue of standing in climate litigation has been controversial, with federal courts often issuing contradictory rulings — some courts have ruled that only states have proper standing in climate litigation, like the case of Massachusetts vs. EPA, which paved the way for the Environmental Protection Agency to regulate greenhouse gases as a pollutant.

And some reports suggest that, if the case proceeds to trial, the Trump administration will attempt to recruit scientists skeptical of the mainstream consensus on climate change in an attempt to undercut certainty around climate science. Ninety-seven percent of publishing climate scientists agree that climate change is both happening and a product of human activity, though a small, vocal minority has found particular quarter within the Trump administration. Trump himself as repeatedly cast doubt on climate science, calling it a “hoax” created by the Chinese, and has appointed climate-deniers to top posts within his administration.

Regardless of what happens on Monday, the youth climate lawsuit is far from the only piece of climate litigation working its way through the U.S. court system. In California, five communities — two counties and three cities — are suing fossil fuel companies for their role in climate-fueled sea level rise, hoping to recoup the costs of climate mitigation projects to protect against flooding and coastal erosion. And in Pennsylvania, two children are suing the Trump administration over its anti-climate, anti-regulatory agenda, arguing that the administration’s actions are based on “junk science” that knowingly increases the “damages, death and destruction” of climate change.

"The master class has always declared the wars; the subject class has always fought the battles. The master class has had all to gain and nothing to lose, while the subject class has had nothing to gain and everything to lose--especially their lives." Eugene Victor Debs